Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

1 files changed, 76 insertions, 0 deletions

diff --git a/fs/9p/cache.c b/fs/9p/cache.c
new file mode 100644
index 000000000..12c0ae29f
--- /dev/null
+++ b/fs/9p/cache.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * V9FS cache definitions.
+ *
+ *  Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
+ */
+
+#include <linux/jiffies.h>
+#include <linux/file.h>
+#include <linux/slab.h>
+#include <linux/stat.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <net/9p/9p.h>
+
+#include "v9fs.h"
+#include "cache.h"
+
+int v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses,
+				  const char *dev_name)
+{
+	struct fscache_volume *vcookie;
+	char *name, *p;
+
+	name = kasprintf(GFP_KERNEL, "9p,%s,%s",
+			 dev_name, v9ses->cachetag ?: v9ses->aname);
+	if (!name)
+		return -ENOMEM;
+
+	for (p = name; *p; p++)
+		if (*p == '/')
+			*p = ';';
+
+	vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
+	p9_debug(P9_DEBUG_FSC, "session %p get volume %p (%s)\n",
+		 v9ses, vcookie, name);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			kfree(name);
+			return PTR_ERR(vcookie);
+		}
+		pr_err("Cache volume key already in use (%s)\n", name);
+		vcookie = NULL;
+	}
+	v9ses->fscache = vcookie;
+	kfree(name);
+	return 0;
+}
+
+void v9fs_cache_inode_get_cookie(struct inode *inode)
+{
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct v9fs_session_info *v9ses;
+	__le32 version;
+	__le64 path;
+
+	if (!S_ISREG(inode->i_mode))
+		return;
+	if (WARN_ON(v9fs_inode_cookie(v9inode)))
+		return;
+
+	version = cpu_to_le32(v9inode->qid.version);
+	path = cpu_to_le64(v9inode->qid.path);
+	v9ses = v9fs_inode2v9ses(inode);
+	v9inode->netfs.cache =
+		fscache_acquire_cookie(v9fs_session_cache(v9ses),
+				       0,
+				       &path, sizeof(path),
+				       &version, sizeof(version),
+				       i_size_read(&v9inode->netfs.inode));
+	if (v9inode->netfs.cache)
+		mapping_set_release_always(inode->i_mapping);
+
+	p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
+		 inode, v9fs_inode_cookie(v9inode));
+}